Methylene citric acid and process of making same.



UNTTETT STATES PATENT ()FFICE.

WILHELM STERNBERG, OF BERLIN, GERMANY, ASSIGNOR TO Ol-IEMISCHE FABRIKAUF ACTIEN, (VORM. E. SCHERINGQ OF BERLIN, GERMANY.

METHYLENE CITRIC ACID AND PROCESS OF MAKING SAME.

SPECIFICATION forming part of Letters Patent N 0. 699,422, dated May 6,1902.

Application filed October 29, 1901. Serial lilo. 80,449. (No s ecimens.)

To (all whom it may concern:

Be it known that I, WILHELM STERNBERG, chemist, doctorof philosophy,asubject of the Emperor of Germany, residing at Berlin, Kingdom ofPrussia, German Empire, have invented a new and useful Improvement inMethylene Citric Acid and Method of Making the Same,of which thefollowing is a specification.

My invention relates to the manufacture of the hitherto-unknownmethylene citric acid, which is of use in medicine.

To manufacture methylene citric acid one proceeds, for example, asfollows: Twentyone kilograms of citric acid are heated with fourkilograms of polymeric formaldehyde (paraformaldehyde,trioxymethylene)to from 140 to 160 centigrade until the clear solution first producedbegins to become cloudy and deposit crystals. The product of thereaction is then gradually allowed to cool to about 100. It is dissolvedin from twentyfive to thirty kilograms of Water and filtered. Theseparated crystals are filtered, washed, and dried.

It is possible, but not so preferable, to al low a solution of formicaldehyde to react upon the citric acid in the presence of a condensingagentsuch as, for example, hydrochloric acid or sulfuric acid.

Methylene citric acid melts at 208. It is water.

ble in the presence of acids, but less stable in the presence ofcarbonic acid and caustic alkalies.

Medicinallyvaluable salts of methylene citric acid can be formedsuch asthe silver salt, the mercury salt, the magnesium salt, and thehexamethylentetramin salt. The latter is easily soluble in water, thusdiffering from methylene citric acid.

Methylene citric acid is useful for the disinfection of the urinarypassages and for the treatment of uric acid diathesis. It is preferablyadministered in doses of from 0.5 to one gram three times daily.

I claim as my invention 1. The herein-described process of manufacturing methylene citric acid, which consists in causing formaldehyde,preferably in a polymeric state, to react upon citric acid and isolatingthe resulting product, substantially as set forth.

2. As a new product the herein-described methylene citric acid, beingawhite crystalline powder, difficultly soluble in cold but easily in hotwater, and melting at 208 centigrade.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

WILHELM STERNBERG.

Witnesses:

WOLDEMAR HAUPT, HENRY I'IASPER.

